Merge pull request #32172 from overleaf/dn0-fix-server-ce-dockerfile-syntax

[server-ce] fix Cloud Build by adding Dockerfile syntax directive

GitOrigin-RevId: 007c4fcf571165c7c1cea311771468662f022a43

server-ce/Dockerfile

@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1-labs
 # ---------------------------------------------
 # Overleaf Community Edition (overleaf/overleaf)
 # ---------------------------------------------